Abstract A transistorized frequency modulator including a Clapp-type oscillator having a transistor and a frequency defining circuit connected across the emitter and collector of the transistor, the frequency defining circuit comprising an inductive element and a plurality of capacitive elements wherein one of the capacitive elements is replaced by a variable capacitance diode. The modulating signal is provided to the terminals of the variable capacitance diode and a portion of the modulating signal is supplied directly to the emitter of the transistor so that the collector current increases when the capacitance of the variable diode decreases in response to the variation of the voltage of the modulating signal.
In a transistorized frequency modulator of the type including a Clapp-type oscillator having a transistor and a frequency defining circuit connected across the emitter and collector of the transistor and composed of an inductive element and a plurality of capacitive elements, the improvement for improving the oscillation frequency versus output power characteristics of the modulator comprising a variable capacitance diode substituted for one of said capacitive elements; means for supplying a modulating signal across said variable capacitance diode; and, means connected to said signal supplying means and said variable capacitance-diode for supplying a portion of said modulating signal to one control terminal of said transistor, thereby to increase the collector current when the capacitance of said variable capacitance diode decreases in response to a variation in the voltage of said modulating signal.
Claim 2
Dependent Claim
132 words
In a transistorized frequency modulator of the type including a Clapp-type oscillator having a transistor and a frequency defining circuit connected across the emitter and collector of the transistor and composed of an inductive element and a plurality of capacitive elements, the improvement for improving the oscillation frequency versus output power characteristics of the modulator comprising a variable capacitance diode substituted for one of said capacitive elements; means for supplying a modulating signal across said variable capacitance diode; and, means connected to said signal supplying means and said variable capacitance-diode for supplying a portion of said modulating signal to one control terminal of said transistor, thereby to increase the collector current when the capacitance of said variable capacitance diode decreases in response to a variation in the voltage of said modulating signal.